There have been many attempts over recent years to manufacture fabrics having conductive elements therein, useful for a variety of applications including communication, powering peripheral devices, data transfer or collection, sensing and the like. Early devices sought to form multi-layered structures, intended to create physical separation between the plurality of conductors in the structure. These devices, however, were bulky, unreliable and prone to delamination.
In the applicant's earlier EP-1,269,406 and EP-1,723,276 fabric weave structures are disclosed which have proven to provide a reliable conductive fabric structure with inter-crossing conductive yarns which may be kept separate from one another, arranged to touch one another under pressure or permanently connected together. There are also described electronic components formed by the conductive yarns. The structures disclosed in these applications have been found to work very reliably and to have good longevity. There is now a need for a fabric having larger conductors, for example for delivering more power through the fabric, and for use in harsh and demanding conditions.
Other examples of conductive fabrics can be found in U.S. Pat. Nos. 3,711,627 and 3,414,666. The disclosures in these documents disclose impregnating the fabric with plastic substances such as polyester resins or an elastic insulating compound for reliability and preventing short circuits. However, coating or impregnating a textile is undesirable for a number of reasons. It adds expense and additional complication to the manufacturing process, as well as rendering the textile heavier, thicker and stiffer. These latter effects compromise some of the very qualities that may be sought and desirable from the outset in a conductive textile.
It is important to minimize the risk of undesired short circuiting of the conductors in the fabric. This risk increases when the textile is worn upon the body, where it can be subjected to bending, creasing and the incidence of pressure. The risk is also greater when the diameter of the conductive yarns is larger, which limits the diameter of conductive yarns which may reliably be employed, in turn limiting the linear conductivities of the yarns. This results in increased resistances within the textile circuits created, which decreases electrical efficiency and ultimately limits the operating current and power of the circuits.